The 20th of May is the UN World Bee Day, so take a moment to consider all the pollinators visiting flowers this Spring.
A honey bee visiting a flower. Image Credits: Krzysztof Niewolny on Unsplash.
On a bright morning in early May I found myself walking along the residential streets of the coastal Scottish town where I live. I was on my way to the beach and Spring was in full swing; the weather was warm, the birds were out, the trees were showing the vibrant green of new growth. I walked past a low brick retaining wall which was leaning slightly with the weight of earth behind it. The wall had evenly spaced gaps in the brickwork for drainage. The black bodies of solitary bees were waving through the air in front of the wall. They were zooming in from their rounds of the town’s garden flowers, abruptly slowing down, then zigzagging their way to a landing in the drainage holes. In this urban landscape, these animals had found a place to build their nests and make their home.
There are about 275 species of bee in the UK. Most of us are familiar with honeybees and bumblebees but these make up only 10 percent of UK bee species. The rest are solitary bees, but even these are just the beginning of pollinator biodiversity. Hoverflies, butterflies, moths, wasps and beetles all play a role in pollination in the UK. The conservation of all of these species is essential to maintain a healthy environment.
A hoverfly visits a flower. Image Credits: Marjon Besteman on Pixabay.
A decline in the numbers of insects has been widely documented, but is troubled by the shifting baseline effect and insufficient records prior to the 1970s. Butterflies and bees are better studied than other pollinators. Indicators for farmland and woodland butterfly abundance in England declined by 47 and 59 percent respectively between 2000 and 2009. The ranges of many bumblebee species in the UK have changed dramatically, and 3 of the original 25 species have become extinct here.
The loss of pollinator species in a land as intensively cultivated as the UK likely began hundreds, if not thousands of years ago. In the last century however, the more intense cultivation of the land coupled with climate change, invasive species, pesticides and light pollution have accelerated the loss of insect biomass and biodiversity. Awareness of this issue is increasing though, and this has led to positive changes.
From the 1990s to 2010s there was rapid growth in a new class of insecticides called neonicotinoids which target the nervous systems of insects. They were a commercial success because of their high toxicity to insects and relative safety for vertebrates. However the new insecticides carried poorly understood risks to the wider environment which only came to light well after their introduction. Neonicotinoids can be applied to crop seeds and when this is done up to 94 percent of the pesticide disperses into the environment. These chemicals were also detected in pollen, with obvious implications for pollinators.
In 2013 the EU placed a temporary moratorium on the use of three of the most harmful neonicotinoids for flowering crops, and this was later extended to all crops. After leaving the EU, the UK has maintained the ban on the most harmful of these pesticides. However, one of the less environmentally persistent neonicotinoids, acetamiprid, is still in use in the UK and EU. Additionally, the British government has granted an emergency authorisation for sugar beet farms to use thiamethoxam, one of the banned neonicotinoids, every year since 2022. Various environmental organisations have opposed this yet authorisation has been extended for 2024.
Environmental organisations, alongside veterinary groups, have also called for an end to the use of certain insecticides in pet medications such as flea treatments. Some of these medications contain neonicotinoids never approved for use in agricultural settings. These substances make their way into the environment, and have been widely detected in British waterways at levels unsafe for wildlife.
A peacock butterfly visits a flower. Image Credits: Uschi Dugulin on Pixabay.
While insecticides are an invisible threat to pollinators, there are other threats we often see without considering. We are all familiar with the way outdoor lamps attract an entourage of night time critters that orbit and crash into the bulb. What many of us forget is that pollination takes place in the night too. Insects which spend their whole night at the local lamp post have no time left for pollination.
There is also a less visible impact on insects which are photophobic, and avoid areas where lamps are turned on. One study found a 29 percent reduction in pollinator species visitation (and 62 percent all insect visitation) to artificially illuminated cabbage thistle. This is one area where simple individual actions can make a contribution. Just switching off outdoor lighting and closing curtains benefits the inhabitants of the dark.
Loss of the darkness has been compounded by habitat loss in pollinator decline. Much of this is historic in the UK, however loss of wildflower habitat, expansion of urban areas and an intensification of agriculture have continued to impact pollinator species. Climate change has consequences here too. The warming climate tends to push the range of species to higher latitudes or altitudes. However fragmented habitats surrounded by large swathes of ecologically deprived land can make it difficult for pollinator species to make such multi-generational moves.
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